Abrasive tool



Dec. 23, 1952 A F E D 2,622,377

ABRASIVE TOOL Filed Feb. 15, 1950 INVENTOE flLBEZT HELD ATTORNEYS.

Patented Dec. 23, 1952 UNITED STATES PATENT OFFICE Application February 13, 1950, Serial No. 143,893

1 Claim. 1

The present invention relates to abrasive tools employed for polishing or finishing metal, rubber and plastic materials and an abrasive element for'use in connection with such tools, also an improved method for making such elements.

In my Patent No. 2,410,870, granted November 12,1946, there is disclosed an abrasive tool of conical configuration in which the convolutions are'secured together by a glued edge. The abra- 'sive piece when laid flat, i. e. before being wound on a tapered mandrel, is provided with a rounded edge subtended by'two rectilinear edges arranged at substantially right angles to one another. When one of these right-angle edges is inserted into a slot or keyway of a tapered mandrel and the latter is rotated, the abrasive member is wound to form a conical element with an external abrasive surface, the convolutions being secured together by the adhesive. The general shape of the wound element is strictly conical in that it is formed to a fairly sharp point and the edge of the abrasive piece will be found to define an ascending spiral as it proceeds up the tapered surface of the mandrel toward the mandrel portion of maximum diameter. The uppermost portion of the conical element, i. e., the uppermost edges of theelement which are formed by the curved edge of the abrasive piece, defines a flat end surface and the edges at this point areheld together by the adhesive. 7

, An abrasive element of the character described isused in connection with a working arbor or shaft having a tapered end which fits the tapered hole of the element and is provided with threads which are adapted to engage the glued or flat end of the element, i. e. remote from the conical tip. While an abrasive tool of this type operates satisfactorily, nevertheless since the tip portion of the element is drawn down almost to a point, -it hasbeen found that the tendency to wear is concentrated at this end. Moreover, inasmuch as the working arbor cannot extend as far as I the extreme tip of the cone, little or no reinforcean abrasive tool of conical configuration with a blunt or square end over that portion of the tool or element which derives no reinforcement from the tapered arbor. Thus the blunt or square end of the tool provides its own reinforcement.

, ,Another object ,is to provide an abrasive tool' formed of spirally wound strip material terminatmg in a substantially rigid self-supporting'p'ortion, instead of a flexible pointed portion.

Still another object is to provide an abrasive tool formed of abrasive strip material wound on itself with the abrasive side of the material external of the tool, and having one edge of the strip exposed and moving inwardly and upwardly as the winding proceeds to form a cone, the end of the cone being characterized by a portion of substantial diameter.

A further object is to provide an abrading tool formed of abrasive strip material, wound cone fashion with partially overlapping convolutions, the cone being characterized by two end portions of uniform diameter but of different size over appreciable portions of the end lengths of the cone.

Another object is to provide an abrasive element in the form of a frustum of a cone composed of a single rolled strip of flexible abrasive material, provided with a central bore element, one end of the cone being comparatively unyielding to provide firm bearing for attachment to a mandrel or the like, and wherein the opposite or working end of the cone is substantially inflexible and without appreciable resilience whereby to withstand considerable transverse pressure against the end of the cone which would be exerted by the workpiece being polished or finished. I

A further object of the invention is to provide an abrasive tool of inexpensive construction comprising mandrel and abrasive elements having a frustro conical shape in which the elements may be easily and quickly attached to the mandrel for firm interlocking connection therewith so as to enable quickreplacement of the tools as may be necessary and in which the mandrel and the cone elements are so formed that their cooperative relation produces an abrasive tool, the working end of which may be firmly engaged with articles to be abradedly finished thereby.

The above objects are attained in brief by using for the abrasive cone, a strip of abrasive material perforated along one edge and provided with adhesive on the surface which has been roughened by these perforations, the strip having such shape that when wound in overlapping fashion and the convolutions held together by the adhesive the end of the element remote from the place where the mandrel is inserted becomes a stubby self-supporting portion.

Other objects and features will become apparent when the following specification is perused in connection with the accompanying drawings in which:

Figure 1 illustrates a winding or manufacturers mandrel employed in making an abrasive tool of the improved character;

Figure 2 shows the abrasive piece or strip inserted in the winding mandrel to constitute the start of the winding process;

Figure 3 illustrates a shank or the working mandrel of the improved abrasive tool;

Figure 4 depicts the manner in which the convolutions of the abrasive strip are wound on each other to form a self-supported unit secured to the shank member or working mandrel;

Figure 5 represents an end or elevational view of the unit and shaft shown in Figure 4;

Figure 6 illustrates the abrasive strip in a flat, V

Figure '7 is a view, partly in longitudinal sec tion, and partly in elevation, of the completed abrasive cone; and

Figure 8 is an enlarged sectional View through a portion of the cone.

Referring to Figure l, the element designated I constitutes a windingarbor or'mandrel employed by a manufacturer in forming the improved abrasiveJelements. It is constituted of a long shaft portion 2 containing a longitudinal slot -3 and formed witha portion 6 of larger diameter to be inserted into the chuck of alathe. Th manner in which the abrasive strip 5 is first inserted into the slot 3 and then wound to form the frusto-conicalabrasive element which is the subject of this invention is shown in Figure 2.

The strip 5 has abrasive material 6 on the opposite side from that shown on the drawing and is plain on the front side. Any suitable and well known type of abrasive cloth or paper may be employed, or if desired, even sandpaper or sandcloth. The strip (Fig. 6) is characterized by a longitudinal edge 1 of rectilinear shape and has ends 8, 9 preferably extending at-right angles to the edge I. The opposite longitudinal edge is-constituted of two rectilinear portions I9, II

the'edge I0 extending parallel to the edge I for a substantial distance away from the edge 8 to a point I2, and the rectilinear'edge II which is tapered downwardly extends from the point I2 to the edge 9. Thus these edges are positioned angularly with respect to one another, the upper edge of the strip as seen in Figure 6 extending first parallel to the opposite or lower edge and then tapering down in a straight line to form a narrow strip width at the edge 9. The purpose of these angularly related edges I0, II will be explained when the formation of the cone is described.

In order that the layers or convolutionsof the strip when wound shall be firmly secured together, the smooth side of the emery cloth .or emery paper is roughened byperforating the cloth or paper as'indicated at I3, these perforations being formed from the abrasive side and extending to the smooth side in ordert'o, provide upset edges I4 (Fig. 8) aroundeach perforation on thesmooth side of the strip. These upset edges-tend to roughen the smooth side ofthe strip. and to provide. a more 'firm, adhering property when a narrow width of adhesive I5 is applied over this roughened portion of the strip along the edge I as seen .inFigure 6. This perforating process can be accomplished by any suitable type of perforating machine in which the. device enters the strip by first engaging the abrasive surface 6 thereof and then passing through the fabric or other .material of the stripto cause said material to break out from the smooth surface to roughen said surface in the region of the perforations.

It is apparent that some of the glue or other adhesive so applied passes through the perforations previously provided at the points I3 to insure that a sufficient amount of glue is applied between adjacent layers of the strip 5 comprising the conical roll. This produces a tight binding of such adjacent layers at the inner end of the cone provided by the edge I of the strip.

The strip is wound into the shape of a frustum of a cone by inserting the wide end formed of edges 1, I0 into the slot 3 of the working mandrel as seen in Fig. 2. When the latter is rotated as in any suitable manner, for example by means of the chuck of a lathe or drill-press and the strip is properly guided so as to maintain the edge? in a, flat condition as the winding proceeds, an abrasive element I6 will be formed similar to that shown in Figure l. The glued surface I5 will hold these convolutionsfirmlytogether, this adhesion being greatly increased by the roughened surface caused by the perforations I3. Since the edges 1 of the overlying convolutions are firmly secured together in the manner described, the winding mandrel 2 may be removed simply by untwisting for about a quarter of a turn to release the end of the strip from the slot 3. The element may then be used as an abrasive tool by providing .a working arbor or shaft I1 adapted to fit into the chuck of a drill-press or lathe and having a shouldered portion I8 which tapers over a threaded portion I9 to a shank portion 28. This shank may be pressed into the opening left by the winding mandrel and the threads will engage the edge of the opening at the surface I firmly to secure the element to the mandrel.

The edges It and I I of the strip5 are provided with the proper angularity and the distance of the point I2 from the edge 8 is so predetermined that when the element I6 is wound, the end of the element remote from the mandrel II takes on a stubby or square formation anddoes not develop to a point. I Thus the general form of the abrasive element is that of a frustum of a cone. The advantage of this stubby or square endof the cone is that this end'portion becomes selfsupporting at a position where very little if any reinforcement can be offered by the shank portion 2!] of the working mandrel. Thus the working end of the cone is of rigid construction and since there is no bend or pliability to this end, the abrasive cloth'or sandpaper tends to maintain its firm, unbroken-construction and therefore provides greater life to the element as a whole. The manner in which the end represented by the edge I0 provides this stubby construction or shape is shownvin Figure 7 where it will be noted that at least two convolutions or layers 2I are wrapped over one another for the full width of the strip to give firmness at this point before the edge II starts its spiraling movement.

While I have shown and described-my improved abrasive element as being constituted of strip material wound to a frustro-conical configuration and in which protrusions are formed on the smooth side of the abrasive cloth or sandpaper and adhesive applied over these protrusions, it will be understood that any other suitable manner of securing these convolutions together may be employed asv a feature. of this invention resides mainly in providinga stubby or square end to the element by so cutting the strip that an abrasive element of conical shape but without a pointed tip is accomplished.

The details of securing the convolutions together along the edge I of the strip are disclosed and claimed in my Patent No. 2,140,870, patented November 12, 1946.

It will be understood that various modifications and arrangements in structure could be made Without departing from the spirit of my invention and, accordingly, I desire to comprehend such modifications and substitutions of equivalents as may be considered to come within the scope of the appended =claim.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent, is:

An abrasive tool comprising a coated abrasive strip wound upon itself in a plurality of contacting convolutions adhesively secured together with one edge of successive convolutions lying in a, single trans-axial plane at the base of the tool and the other edge stepped back in uneven amounts to leave a, curvilineal abrading surface with a blunt, rigid end working portion and exposing the abrasive surface of the successively wound convolutions, said strip having a rectilineal edge 'where the adhesive is applied, and

an angular edge opposite thereto, said last mentioned edge being formed of two straight lengths, one of which extends parallel to the rectilineal edge to which the adhesive is applied, and the other length tapers with respect to said last mentioned edge, the strip portion of greater width forming said rigid working end, and a mandrel entering said tool from the base thereof for rotating the tool, said mandrel extending for only a limited distance into said tool as far as the beginning of said blunt, rigid end portion, whereby the last mentioned portion maintains its rigidity notwithstanding the absence of support by the mandrel at said blunt end.

ALBERT FIELD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 240,829 Kimball May 1881 691,066 Miller Jan. 14, 1902 736,114 Koenig Aug. 11, 1903 1,119,760 Koontz Dec. 1, 1914 2,290,098 Field July 14, 1942 2,358,724 Manchester Sept. 19, 1944 

